You can have your own indoor paddling setup with a balance ball and a dowel. You can rest your feet on a stable object, a smaller ball, or no object at all.
Sequence your stroke with a dowel. Sitting or standing follow these steps: 1) Catch with the high hand, 2) Rotate until dowel is at your hips, 3) Exit with back of the hand, and 4) Continue rotation to set up for next stroke. Start with very distinct and mechanical movements and gradually smooth the movement into one fluid movement. The goal of the drill is to learn to continue your rotation after you exit.